Different kinds of collapsible frame structures for playards or play pens for infants, toddlers and children are known. One known structure is composed of top rails, pairs of rods arranged in an X-shape along the sides of the structure and a locking hinge arranged between each top rail and each pivot point of the rod pairs. Also known is a box structure that includes four frame legs and four upper frame joints and four lower frame joints pivotally connected to the frame legs. The structure also includes a bottom base frame with four legs radially extending from a central coupling joint, which allows the four legs to fold. U.S. Pat. No. 7,418,746 discloses a collapsible frame structure that includes a plurality of legs and paired cross-members extending between adjacent legs and a plurality of slider joints engaging the legs and pivotably attached to two adjacent cross-members. Additional United States patents disclosing collapsible play pens include U.S. Pat. Nos. 7,503,085 and 7,036,161.